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Residential Whole Loans - Allowance for Credit Losses (Details) - Residential whole loans - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2026	Jun. 30, 2026	Mar. 31, 2026	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2025
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 9,393	$ 9,437	$ 9,705	$ 9,949	$ 10,194	$ 10,665
Current provision/(reversal)	45	(62)	(242)	276	791	145
Write-offs	(1,485)	18	(26)	(142)	(1,036)	(616)
Ending balance	7,953	9,393	9,437	10,083	9,949	10,194
Non-QM loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	5,761,774						$ 5,346,693
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,292	1,408	1,725	2,015	1,928	2,125
Current provision/(reversal)	126	(116)	(317)	205	87	(197)
Write-offs	0	0	0	(38)	0	0
Ending balance	1,418	1,292	1,408	2,182	2,015	1,928
Business purpose loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,999,999						2,443,328
Business purpose loans \| Single-family rental loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	1,058,094						1,235,346
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	920	762	918	937	980	366
Current provision/(reversal)	(6)	158	(156)	(78)	(43)	614
Write-offs	(42)	0	0	(30)	0	0
Ending balance	872	920	762	829	937	980
Business purpose loans \| Single-family transitional loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	678,457						718,345
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,542	1,156	1,042	512	865	1,389
Current provision/(reversal)	279	386	114	548	669	(88)
Write-offs	(1,416)	0	0	0	(1,022)	(436)
Ending balance	405	1,542	1,156	1,060	512	865
Business purpose loans \| Single-family transitional loans \| Collateral Dependent Methodology
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	3,800			3,800
Seasoned RPL/NPL loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	885,318						$ 979,016
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5,639	6,111	6,020	6,485	6,421	6,785
Current provision/(reversal)	(354)	(490)	117	(399)	78	(184)
Write-offs	(27)	18	(26)	(74)	(14)	(180)
Ending balance	5,258	$ 5,639	$ 6,111	6,012	$ 6,485	$ 6,421
Seasoned RPL/NPL loans \| Collateral Dependent Methodology
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans	$ 23,200			$ 32,100